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                Pku2422 The Wolves and the Sheep                </h1>
                <p>时间限制：30s&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;  空间限制：259MB</p>			</div>
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                                <h3>题目描述</h3><p>三只狼和一只羊在一片草地上相遇了~ 群狼很饥饿,后果很严重……
草地是一个R*C的矩形，矩形内“X”点代表石头是不能过的，“.”代表草地。狼用“W”表示，羊用“S”表示。
狼和羊交替的走，轮到狼走的时候，可以选择3只中的任意一只走一步，如果三只狼都走不动，那么可以不走。轮到羊走的时候，羊必须走。
如果某个时候羊不能走了，即它被围住了，那么羊就要被吃掉了，否则的话如果它逃出了草地，那么它就得救了。狼想知道他们能不能在有限步内围住羊然后美餐一顿。

</p><hr/><h3>输入格式</h3><p>首先两个数R,C
接下来一个R*C的矩阵描述草地。
多组数据，处理到文件尾。

</p><hr/><h3>输出格式</h3><p>如果狼能围住羊，打印danger，否则打印safe。

</p><hr/><h3>样例输入</h3><pre>4 5
..X.X
W..X.
....W
.SWX.

5 5
..WXS
W.WXX
...X.
.XX..
..X.X

4 4
.WW.
...S
.XX.
..W.

4 4
S..W
X.X.
....
..WW

5 5
...W.
.X...
XW..X
..S.X
.W...

5 5
XXXXX
X...X
XXW.X
XWWSX
XXXXX

5 4
X.W.
SXXW
..X.
.W..
X...

4 5
XXXXX
XS.WX
XWW.X
XXXXX

5 4
..X.
..X.
..X.
WX.S
W.W.

4 5
XXXXX
XW.SX
X.WWX
XXXXX

</pre><hr/><h3>样例输出</h3><pre>safe
safe
safe
safe
safe
danger
safe
danger
safe
danger
</pre><hr/><h3>提示</h3><p>
对于40%的数据保证 
对于100%的数据保证 
数据组数小于等于10。
</p><hr/><h3>题目来源</h3><p>没有写明来源</p>
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